U.S. Pat. Nos. 3,506,587 and 3,522,190 to Turner et al and U.S. Pat. No. 3,642,651 to Marboe et al describe photoluminescent glasses. In greater detail, Turner et al, U.S. Pat. No. 3,506,587, describe high intensity photoluminescent glasses comprising aluminosilicates and aluminoborosilicates containing alkaline earth metal oxides, but being substantially free of alkali metal oxides, and containing an effective amount of a luminescent activator to convert incident ultraviolet into usable visible illumination. The luminescent activator consists of at least two members of the group of tin oxide, copper oxide and samarium oxide.
Turner et al, U.S. Pat. No. 3,522,190, disclose photoluminescent glass compositions, particularly magnesia-alumina-silica glasses, doped with samarium partially reduced to the divalent state.
Marboe et al disclose photoluminescent glasses of borate, phosphate, or silicate containing a germanium compound, such as germanium dioxide, as an activator.
Materials which exhibit fluorescence in response to ultraviolet light are becoming increasingly significant in many practical applications, such as increasing the output of mercury vapor lamps and use in display panels, indicator lamps, decorative illumination, etc. Accordingly, additional photoluminescent glasses are constantly being sought. The present invention provides certain such materials.